Alkylation of ethylene mixed feeds



g ,1946. :c. s. LYNCH ETA; 2,405,968

ALKYLATION OF ETHYLENE MIXED FEEDS Filed May 25; 1945 5-" 7'0 sums/4125a- I I [563 774015 v r550 1,

. A; REAcTon ETHYL ENE.

SCRUEBEZ M11522 raw INLET Recently it has been "an extended period of lystpossessing a long factory. It has furtherbeen found in that when Working at its in a supercharged engine.

Patented Aug. 20, 1946 2,405,968 ALKYLATION OF ETHYLENE lVlIXED FEEDS Charles S. Lynch, Plainfield, and Howard G.

Codet, Mountainside, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application May 25, 1943, Serial No. 488,344

6 Claims. (C1. 260--683.4)

The presentinvention relates to improvements in the art of alkylating ethylene mixed feeds, and more particularly, it relates to a continuous operation of catalytically alkylating ethylene with isoparaffins in which the ethylene feed stock is mixed with other hydrocarbons and gases and in which the alkylation is accomplished in a manner which is cheaper than has been possible heretofore.

be alkylated with isobutane to form hydrocarbons boiling within the gasoline range, of high octane number, incIudingZB-dimethyl butane. It has been-found in connection with these researches that the catalyst prepared by contacting the isoparaffin and the olefin with aluminum chloride for time is a brown mobile is an aluminum chloride which is an active catalife and is otherwise satisconnection with these prior researches that the alkylation may be carried outat ordinary atmospheric temperatures or above. For example, the alkylationmay be carried out at temperatures from 65*-200 F. with a range of 90l25 F. preferred. It has further been found that a small amount liquid which apparently hydrocarbon complex,

of volatile halide incorporated with the isobutane feed greatly improves Thus, from 1 to 15% chloride based on the fin greatly increases the quality and the yields. of, ethyl chloride or methyl isobutane or other isoparafthe efficiency of the process. About 5-10 volume per cent of ethyl chloride gives the best results. Further, it has been found that pressures of from 100-1000 lbs/sq. in. give good results with pressures of the order of 200- '300 lbs. preferred. The researches have also revealed that the fresh feed to the reaction zone should have an excess of the isoparafiin, that is to say, best results are obtainable when the fresh feed contains 3 mols of isoparafiin to each mol of olefin. With respect to the amount of aluminum' chloride, it has'been found that by maintaining from 3 to 100, and preferably about 20 weight 'per cent of aluminum chloride in the reactor" gives optimum results. Under the conditions stated, numerous runs have demonstrated best, the foregoing process is adapted to produce an alk'ylate over 60 volume per cent of which contains Cs hydrocarbons; including 2,3-dimethyl butane. 2,3-dimethylbutane is a hydrocarbon which has a high 'octane number but is particularly valuable because of its excellent rich mixture performance found that ethylene may- 2 Our present invention relates to that phase-of the above indicated process which includes separating the ethylene from the gases'with which it is associated as it is fed to the systemlbefo're contacting the catalyst in the alkylation process. ,In other words, in a commercial refinery the normal C2 or ethylene fraction will be associated with neighboring hydrocarbons and hydrogen. In other words, the C2 hydrocarbons will containin addition to the desired lefin, methane, ethane,

and hydrogen. The parafiins, of course, are inert, and if they flow through the systemwith the ethylene during the reaction, they will eventually have to be eliminated and their'processing' and elimination uselessly, o'fjcourse, requires additional facilities and utilities.

In brief compass, we have devised a-procefss 'for eliminating the unwanted hydrocarbons in the ethylene feed, in a relatively simple andexpeditious manner as will more fully appear. hereinafter. V

In the accompanying drawing we have shown afioW, plan indicating a continuous process for alkylating ethylene with isobutane, including the features hereinbefore mentioned. v

Referring in detail to the drawing, we shall describe a preferred method of alkylating ethylene with isobutane in the presence of aluminum chloride hydrocarbon complexso that a better understanding of our invention may be had.

I is a reactor which, as indicated in the drawing, may be an elongated, cylindrical vessel packed with a material such as Raschig rings. Superposed on reaction vessel I is a settler 2 carrying a pressure gauge 3 disposed in a ventline 5 carrying a liquid level control valve l0. Disposed at the side of the reactor I is a vessel or receptacle 20 in which is contained aluminum chloride,and the feed stock, as will subsequently appear, passes through this container where it absorbs or otherwise acquires aluminum chloride and thenflows into the reactor. The ethylene feed enters the system through a line 25 and the isobutane enters through line 28, the latter being in a liquid condition. At the start of the operation, the isobutane is first introduced into the empty system ylene and isobutane pass upwardly to settler 2 and then are withdrawn through recycle line 40 and returned to the tower 30 for recycling via line 32, but now the recycle stream passes through line 38 and thence through the aluminum chloride receptacle and thence passes into the tower 1.

After the'passage of 3-4 hours, the aluminum chloride will have reacted with the hydrocarbons to form the aforementioned aluminum chloride-" =ilarin. construetionill, [and .-thence passed .into

.the reactor has-before. The containerlfl is thoroughly cleaned ;and recharged with. aluminumzchlor-ide .-for subsequent use-in the process.

.Imotherwords, the preferredmethod of operat- .ing thenprocess is to provide two or'more con- :tainers-Miand ZOaandafter one has been in .use vfor some time, it willbe withdrawn vfrom the cir- ..culating system, "thoroughly cleaned and re- .charged' "with fresh -zaluminum chloride.

.The

.other container will imeanwhile bev on stream. -Theuseof itwo -or more-containers 20 maintains continuityot operation even. though itis neces- :sary to addlaluminum chloride periodically to the system. to maintain. the catalyst activity as previously indicated. It: will. benoted thata por- ..tionof thelrecycl product in line.32 maybypass -the.container 2 0 or slim-and pass directlyinto the reactor 1 throughzlineflfi. We-maintain a consumption. .of.,aluminum chloride in our process varying from 0.04 to 0.08 lb. of AlCls per, gallon of-alkylate.

. Thereis .another.,.point. with. respect to the operationoL-the process .and .itis this, .viz., that when the reactorlbecomes filled with catalyst, the A wexcess .passesdntosettler 2, iirom which .it may bewithdrawn byidraweoff ,pipe .8. Actually, .hoW- ever the: system maybe. operated .100hours or more-. before it. islnecessary to withdraw spent catalyst .throughpipe- 8.

. .Except for .the manner cr -introducing the feed stocks; we .haveindicatedthe development of the .alkylationprocessup to thetimeof ourinven- -..tion, whichjinvention willflnow be described .in

detail. .Heretofore,.inoperatingrthe process de- .scribed,,the ethylenefeed and the isobutane feed arehot fed to the system inthe manner we have indicated-in.thedrawing but. are changed directlyto the reactor, andtherefore our improvement comprises, principally, the. interposition of the scrubber 30 into the system. .The mixed feed entering thesaid scrubber-at contains hydrogen, .methane, ethylene,. and possibly ethane, and

contacts.- therein .the .isobutane which enters .ane, ethylene, and ethane.

through;.1ine..28. .The isobutane becomes saturated, of,.course, with respect. tov hydrogen, meth- The ethylene in the course ofQthereactionis continually removed in reactor I, but thehydrogen, methane and ethane .are unchanged-and consequently the recycle .stream in 40 entering scrubber 30, after the processhas been in operation for a suflicient period of time, =is.saturated with respect to all of the .components entering 25, except ethylene, and

hence-onlythe-ethylene is dissolved out of the -ylene..fresh-feed, we are able to reject at once :from thesystem-dnert materials, such as methrrane,'tethane,'hydrogen, and the like, in a simple and expeditious manner.

. Our process possesses particular utility in the processing of an ethylene feed stock which contains a. minor quantity of ethylene, say from 30-40%, such as is obtained, for example, in .steam cracking of hydrocarbons. However, our

process could be used for.feed' stocks containing as low as 10% ethylene in the feed entering through line 25' and this-lowconcentration of ethylene would be highly impractical in an alkylation process where a large preponderance of inert material continuously passed through the system. The temperature of theliquid inthe recycle stream is from 50 to 200 F., preferably from 75 to 125 F., and the pressure is from'100 to 11000 lbs/sq. in., preferably from'200-to; 300

lbs/sq. in.

In operatin our process, as in the previous development of this process, wemaintain-a-molecular excess of isobutaneover the ethylene, Preferably we maintain 3 to mols of isobutane per mol of ethylene in-the reaction zone. The recycle ratio, i. e., theratio of recycled product to fresh feedis from 1 to 30 volumesofrecycle-product per volume of .fresh feed (i. e.,newly added ethyleneand isobutane, disregarding the undesired constituents in the ethylene feed). When operating at its best, verylittle catalyst isin the recycle stream, less than 0.04 weight per cent when. operatingat F.

We. have described in detail the'application of our. invention .to .the alkylationof ethylene and isobutane. It is to be understood'that thesame principle may apply to thealklation of. propylene .or.butylene where the propylene or butylene feeds are mixed or'diluted with relatively large-quantitiesof other. gaseous materials. The removal .of. propane in the scrubbing stepispossiblewhen, as is usuallythe case,.:the pressures;exceed..l25 lbs/sq. in. in the system.

- What we claim is:

1. In the continuous alkylation of-olefins with isoparafiins conducted in the preesnce of an aluminum chloride-hydrocarbon complex formed in situ during the operationof the process, the improvement which comprises first forcing a mixed feed containing a minor proportion of ethylene with an isoparafiin through a reaction zone containing the said aluminum chloride-hydrocarbon complex, permitting the feed stock and the catalyst to'remain incontact with each other for a suflicientperiodoftime toefiect thedesired conversion, withdrawing a product stream, simultaneously withdrawing a recycle stream containing iscbutanev and small amount of alkylate, passing the recycle stream into a scrubbing zone, forcing the mixed feed containing a minor proportion of ethylene .in countercurrent contact with the recycle stream whereuponthe recycle stream becomes saturated .with. undesired x components of the mixed feed containing ethylene, withdrawing the recycle stream enriched with ethylene from the scrubbing zone and returning the same with added isobutane to the reaction zone, continuing the flow of materials in the manner indicated, thus causing mixed ethylene feed, after the recycle stream has becom saturated with undesired components of the fresh feed, to contact said recycle stream whereby said undesired components are rejected by the recycle stream in the scrubbing zone and are adapted to be withdrawn from the scrubbing zone and thus separated from the desired ethylene dissolved in said recycle stream.

2. In the continuous alkylation of ethylene with isobutane in a, continuous operation employing a hydrocarbon AlCls complex catalyst, the improvement which comprises feeding a hydrocarbon stream containing ethylene and undesired components to a scrubbing zone, feeding a recycle product stream substantially saturated with respect to undesired components of the feed to said scrubbing zone, contacting said hydrocarbon stream with said recycled product in said scrubbing zone whereby substantially only ethylene is dissolved in said recycled product, withdrawing the undesired components of said hydrocarbon stream from said scrubbing zone, conducting the recycled product containing dissolved ethylene with added isobutane to a reaction zone containing the said hydrocarbon-A1013 complex catalyst, permitting the ethylene and isobutane to contact each other and the catalyst at elevated temperatures and pressures.

3. The method of claim 2 in which the temperature in scrubbing zone is from about 75 to 200 F.

4. The method of claim 2 in which the pressure in the scrubbing zone is from 200 to 400 lbs/sq. in,

5. The method of claim 2 in which the ethylene feed contains from 50 to 90% hydrocarbons other than ethylene.

6. The method of claim 2 in which the A1013 consumption is from 0.04 to 0.08 lbs. AlCls per allon of alkylate produced.

- CHARLES S. LYNCH.

HOWARD G. CODET. 

